Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
  • B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
  • B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/042—Coating with two or more layers, where at least one layer of a composition contains a polymer binder
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/048—Forming gas barrier coatings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/052—Forming heat-sealable coatings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
  • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
  • C09J123/04—Homopolymers or copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
  • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
  • C09J123/10—Homopolymers or copolymers of propene
  • C09J123/12—Polypropene
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
  • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
  • C09J123/18—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms
  • C09J123/20—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms having four to nine carbon atoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
  • B32B2307/31—Heat sealable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/04—Polyethylene
  • B32B2323/046—LDPE, i.e. low density polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2553/00—Packaging equipment or accessories not otherwise provided for
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/10—Homopolymers or copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2423/10—Homopolymers or copolymers of propene
  • C08J2423/12—Polypropene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2453/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
  • C08J2453/02—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers of vinyl aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof

Definitions

• This invention relates to heat-scalable polypropylene films.
• Polypropylene film is well known fur use as a packaging material. It has high clarity, excellent barrier properties in respect of water vapour and excellent strength particularly when its molecular structure has been oriented by stretching in one or preferably two directions at right angles to each other while subjected to a temperature in the range between 2°C below the crystalline melting point of the polypropylene and its second order transition temperature.
• polypropylene film is inherently heat-sealable to itself and is capable of forming heat-seals of adequate strength at temperatures of about 180°C, at such temperatures and down to about 140°C, oriented polypropylene film will shrink and produce indesirable buckling in the region of the heat-seal.
• heat-sealable polymers examples include polyethylene, copolymers of ethylene with propylene or butene-1, copolyners of propylene with butene-1, and Surlyn (trade mark) ionomers.
• the heat-sealable polymer or copolymers of the heat-sealing layer will provide seals of adequate strength (that is about 300 grams/38 millimetres of seal width - flat jaw sealing) when heat-sealed at temperatures which are as low as possible without being tacky at ambient temperatures, for example, heat-sealing temperatures below about 120°C. There is then a wide temperature range between the minimum heat-sealing temperature to give seals of adequate strength (the "threshold seal temperature") and the temperature at which distortion of the oriented polypropylene film takes place.
• the heat-sealable polymer or copolymer when heat-sealed has immediate strength or tack while hot (“hot tack properties") sufficient to avoid the sealed portions springing apart on retraction of the heat-sealing tools and that it has such good hot tack properties over a wide range of temperatures about the threshold seal temperature.
• an oriented heat-sealable polypropylene film comprises a base polypropylene film having on at least one surface at least two layers of which the outer layer comprises a blend of polybutene-1 with polypropylene in which the polybutene-1 content is from 30 to 95% by weight of the blend and the layer lying immediately below the outer layer comprises a polymer having a preponderance by weight of ethylene and/or butene-1 units.
• polypropylene film we mean a film of a homopolymer of propylene or a copolymer of propylene and another monomer such as ethylene in which the propylene content is at least 85% by weight or a blend of polypropylene with a minor proportion by weight of a compatible polyolefin.
• polybutene-1 we mean the homopolymer of butene-1 or a copolymer of butene-1 with a small proportion of a copolymerisible monomer, for example, ethylene.
• a small proportion in this context will include for instance 2% by weight.
• the blend of polybutene-1 and polypropylene preferably has a polybutene-1 content lying in the range between 50 and 85% by weight, or more preferably in the range between 70 and 80% by weight.
• suitable polymers having a preponderance of ethylene units are low density and high density polyethylenes, ethylene/butene-1 copolymers having greater than 50% by weight of ethylene units,and low density polyethylene resins having carboxylic acids grafted thereto such as are marketed under the trade mark "ADMER". These polymers and copolymers are known per se to be useful as heat-sealable coating compositions for base polypropylene films but have no, or at least limited, hot tack properties.
• Suitable polymers having a preponderance of butene-1 units are polybutene-1, and butene-1 copolymers for example butene-1/ethylene copolymers having greater than 50% by weight of butene-1 units.
• the first and second layers may be applied to the base polypropylene film by any of the known methods including co-extrusion of melts of the materials, melt extrusion, lamination of preformed films and by stretching preformed films in contact with each other to form a unitary film.
• the base polypropylene film may be oriented by stretching in one direction or preferably in two directions substantially at right angles to each other either before or after application of the layers.
• the invention also includes a method of manufacturing an oriented heat-sealable polypropylene film having on at least one surface at least two layers as described herein.
• Table 1 shows the results of eight experimental runs.
• All the co-extruded films were, in each run, quenched on a chill roller then heated to a tu::.perature of about 1000C before being stretched 5:1 times in the machine direction between two sets of nip rollers in which the rollers at the output end were rotated at a greater peripheral speed than the rollers at the input end.
• Each film was then led into a stenter maintained at a temperature of about 150°C and stretched transversely to 9 times its original width. The film was heat-set, cooled,-trimmed at the edges and wound into a roll.
• the threshold scaling temperature and the hot tack temperature range of each of the samples were determined as follows
• a resilient metal blade was used which when bent over upon itself so that the ends touched applied an opening force of 45 grams.
• a strip of a sample film 30 mms wide and of length greater than the blade was laid blend layer downwards along the upper surface of the blade (when in a flat state) with the ends protruding beyond the ends of the blade.
• the blade with sample was then curved over together with the sample on the outside until the ends of the blade and the protruding ends of the sample touched.
• the runs 2 to 8 were repeated but with the blend layer omitted so that the intermediate layers of the runs became the heat-seal layers.
• the threshold sealing temperatures and the hot tack temperature ranges were determined as before and entered into the Table.
• Run 7 shows that a polymer having a preponderance of butene-1 units beneath the layer of the polybutene-1/ polypropylene blend significantly improved the hot- tack properties of the blend and showed some improvement in the threshold sealing temperature.
• the co-extruded film was found to be slightly hazy compared with the resultant films of Runs 2 to 6.
• Run 8 shows that a propylene based polymer layer below the layer of the blend has no effect upon the normal hot tack or threshold sealing temperature of the blend.
• the intermediate layer of polymer was low density.polyethylene (LDPE) in each of the two runs shown in Table 2.
• LDPE low density polyethylene
• the outer heat-sealable layer was varied :s shown in the Table.
• the composite films were made generally as described in Example 1. The results in the columns headed "Layer Material” once again apply to the films under test but with the outer layer omitted.
• Run 1 shows that an outer layer containing only 25% by weight polybutene-1 does not provide adequate sealing or hot tack despite the presence of an intermediate layer of low density polyethylene.
• Run 2 shows that a satisfactory result is obtained when the outer layer contains 50% by weight of polybutene-1.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Laminated Bodies (AREA)
• Wrappers (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (6)

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Citations (4)

• 1981
  • 1981-02-25 GB GB8106003A patent/GB2093765A/en not_active Withdrawn
• 1982
  • 1982-02-16 GB GB8204552A patent/GB2098542A/en not_active Withdrawn
  • 1982-02-16 EP EP82300774A patent/EP0060037A1/de not_active Withdrawn
  • 1982-02-18 AU AU80593/82A patent/AU8059382A/en not_active Abandoned
  • 1982-02-25 JP JP57029767A patent/JPS57157754A/ja active Pending

Patent Citations (4)

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